Hypothalamic lipid‐laden astrocytes induce microglia migration and activation

Obesity‐induced hypothalamic inflammation is closely associated with various metabolic complications and neurodegenerative disorders. Astrocytes, the most abundant glial cells in the central nervous system, play a crucial role in pathological hypothalamic inflammatory processes. Here, we demonstrate that hypothalamic astrocytes accumulate lipid droplets under saturated fatty acid‐rich conditions, such as obese environment, and that the lipid‐laden astrocytes increase astrogliosis markers and inflammatory cytokines (TNFα, IL‐1β, IL‐6, MCP‐1) at the transcript and/or protein level. Medium conditioned by the lipid‐laden astrocytes stimulate microglial chemotactic activity and upregulate transcripts of the microglia activation marker Iba‐1 and inflammatory cytokines. These findings indicate that the lipid‐laden astrocytes formed in free fatty acid‐rich obese condition may participate in obesity‐induced hypothalamic inflammation through promoting microglia migration and activation.